The transport and distribution of potable water uses a network of pipes to move the water, under pressure, to its destination. Up until about thirty or forty years ago pipes for carrying pressurized potable water were made of cast iron or galvanized iron. More recently, pipes for the distribution of pressurized water are generally made of copper or plastic.
All water pipes are subject to rupture because of the expansion of freezing water within them, yet many water pipes are not adequately protected against freezing. Consequently, a lot of pipes are ruptured in freezing weather.
Leaks are also caused by the deterioration of iron pipes over a period of about thirty years. Small pinholes eventually develop because the flow of water under pressure causes deterioration to begin on the inside of iron pipes and to progress outwardly over a period of time.
Water is conventionally carried through pipe systems under from 75 to 100 pounds pressure, and a lot of water under that pressure can escape through just a small hole in a very short time. It is important that the water be turned off just as soon as a leak is discovered. Most homeowners realize the importance of turning off the water and take the responsibility for that initial step. The next step for most homeowners, due to the complexity of the standard repair procedure, is to call a plumber and wait perhaps for days until one is available.